In the manufacturing process of an industrial product, there are many processes of lifting a sample such as a workpiece or raw material or transferring the sample between devices. In a case of lifting the sample or transferring the sample between devices, it is necessary to grab the sample, and a sample-holding device is provided as a device for grabbing the sample.
Examples of a known sample-holding device include a device of a type of physically sandwiching a sample with a manipulator, a magnetic chuck using a magnetic force, a vacuum pad using vacuum, and a Bernoulli chuck using the Bernoulli effect. The Bernoulli chuck is suitable for holding and lifting a thin and smooth sample such as a sheet or a substrate. In addition, since the Bernoulli chuck can hold the sample in a noncontact manner in theory, the Bernoulli chuck does not have negative effects such as attaching an oil film or dirt to the surface of a sample, and making the surface irregular. Therefore, the sample held by the Bernoulli chuck is less damaged by being held. Thus, the Bernoulli chuck is preferably used in a case where a sputtering process or a plating process is included in the subsequent processes.
In contrast, the Bernoulli chuck is disadvantageous in that the suction force of the Bernoulli chuck is less than that of the vacuum pad or the like, and the holding force in a planar direction is particularly weak. That is, the Bernoulli chuck includes a sample-holding surface facing a sample to be held, generates negative pressure by flowing a gas between the sample-holding surface and the sample, and sucks the sample on a sample-holding surface side due to difference in pressure from atmospheric pressure. In the Bernoulli chuck, an air flow is necessary between the sample-holding surface and the sample, a space through which air passes needs to exist between the sample-holding surface and the sample, and the entire surface of the sample cannot be pressed against the sample-holding surface. In addition, it is difficult to create an engagement part preventing movement of the sample in the planar direction, in the space between the sample-holding surface and the sample.
In view of the foregoing, Patent Document 1 proposes a Bernoulli chuck including a positioning member provided on a peripheral surface of a sample-holding surface. In a Bernoulli chuck 300 disclosed in Patent Document 1, positioning members 301 are disposed on the peripheral surface of a sample-holding surface 302 at intervals from each other as illustrated in FIG. 15. The positioning member 301 disclosed in Patent Document 1 is triangular in cross section as illustrated in FIG. 15, and includes an inclined surface. The positioning member 301 disclosed in Patent Document 1 includes a sharp front end 303. Note that the Bernoulli chuck 300 disclosed in Patent Document 1 holds and rotates a sample 305, and does not lift the sample 305. Therefore, the sample-holding surface 302 is directed upward and the positioning member 301 is also provided upward.